FIELD OF THE INVENTION
The invention relates to a combined or integrated engine and transmission control, which utilizes a position of the accelerator pedal to calculate desired values for the engine and the transmission of the motor vehicle.
A drive-train control for a motor vehicle which uses the position of the accelerator pedal to calculate desired values for the engine and the transmission of the motor vehicle and which includes a calculation device, that receives signals proportional to the positions of the accelerator pedal and of the brake pedal and generates therefrom centralized control parameters for the drive train and the brake system of the motor vehicle, is described in a commonly assigned, copending application Ser. No. 08/937,253, filed Sep. 12, 1997. It is also known in the pertinent prior art to support braking processes initiated by the driver by increasing the transmission ratio, i.e., by shifting the transmission into a lower gear. However, this entails the risk of the driven wheels locking when there are slippery roads or generally low coefficients of friction between the tires and the road surface. If the braking process is not regulated by an anti-lock brake system (ABS), for example because the service brake is not active, the brake slip can lead to a loss of driving stability.
In a drive-train controller, of the generic type, use is made, inter alia, of the position of the accelerator pedal, the driving style of the driver, and the ambient conditions of the motor vehicle to calculate setpoints for the transmission of the motor vehicle (see, for example, DE-Z: Automobiltechnische Zeitschrift [Automobile Periodical] 97 (1995) 4, pp 220-224). These, and further influencing variables, affect solely the gear selection of the automatic transmission. The engine controller of the motor vehicle is not influenced by this.
Conventional engine torque controllers (ETC) bring about an increase in the engine torque and thus reduce the brake slip (DE-Z: Automobiltechnische Zeitschrift [Automobile Periodical] 98 (1996) 4, pp. 188-198), without involving the transmission controller.
On the other hand, there are situations in which the driver's wishes and the driving conditions are such that the engine is not in traction mode, i.e. it is not driving the motor vehicle, but it is expedient not to transmit any engine braking torque to the driven wheels.